Pressure Converter

What is a pressure converter?

A pressure converter changes a pressure value from one unit into every other unit at once — pascals (Pa), kilopascals (kPa), bar, pounds per square inch (psi), standard atmospheres (atm), millimetres of mercury (mmHg) and torr. You enter one number, pick its unit, and read all the equivalents side by side, with no lookup tables or manual arithmetic.

Pressure is force spread over an area. The same physical pressure can be written in many units because different fields grew up with different conventions: engineers in the US favour psi, weather and diving use bar and atm, vacuum and medical work use mmHg and torr, and science uses the SI pascal. The underlying quantity never changes — only the label does. This tool relabels it using exact, internationally agreed factors so results stay accurate to seven significant figures.

How does this pressure converter work?

It converts your value to a single base unit — the pascal (Pa) — and then divides by each target unit’s value in pascals. This base-unit method means every conversion uses the same two simple steps, which keeps results consistent and removes the rounding drift you get from chaining conversions.

The exact factor for each unit (its value in pascals) is:

Unit	Symbol	Pascals per unit (factor)
Pascal	Pa	1
Kilopascal	kPa	1,000
Bar	bar	100,000
Pound per square inch	psi	6,894.757
Atmosphere	atm	101,325
Millimetre of mercury	mmHg	133.3224
Torr	torr	133.3224

The two-step formula is:

pascals = value × factor_of_from_unit result = pascals ÷ factor_of_target_unit

So to go directly from one unit to another, you multiply by the ratio of the two factors. For psi to bar that ratio is 6,894.757 ÷ 100,000 = 0.0689476, the familiar psi-to-bar multiplier. A newton per square metre is one pascal, and the pascal is the SI derived unit for pressure, named after Blaise Pascal.

Examples

These worked examples reproduce the converter’s output exactly using the base-unit method above.

Example 1: 1 atm into every unit. Start with one standard atmosphere.

1. To pascals: 1 × 101,325 = 101,325 Pa
2. To kPa: 101,325 ÷ 1,000 = 101.325 kPa
3. To bar: 101,325 ÷ 100,000 = 1.01325 bar
4. To psi: 101,325 ÷ 6,894.757 = 14.696 psi
5. To mmHg: 101,325 ÷ 133.3224 = 760 mmHg

So 1 atm = 101,325 Pa = 101.325 kPa = 1.01325 bar = 14.696 psi = 760 mmHg. This is the standard sea-level atmospheric pressure.

Example 2: 100 psi into bar and pascals. A common tyre or compressor figure.

1. To pascals: 100 × 6,894.757 = 689,476 Pa (689,475.7 to be exact)
2. To bar: 689,475.7 ÷ 100,000 = 6.895 bar
3. To kPa: 689,475.7 ÷ 1,000 = 689.476 kPa

So 100 psi is about 689,476 Pa, roughly 6.895 bar.

Example 3: 100 kPa to psi. A round metric value close to atmospheric.

1. To pascals: 100 × 1,000 = 100,000 Pa
2. To psi: 100,000 ÷ 6,894.757 = 14.504 psi
3. To bar: 100,000 ÷ 100,000 = 1 bar

So 100 kPa equals exactly 1 bar and about 14.504 psi. Notice this is slightly less than 1 atm, which is 101.325 kPa.

Quick reference table

These rounded equivalents cover the most common pressures. Use them as a sanity check against the converter.

From	Pa	kPa	bar	psi	mmHg
1 atm	101,325	101.325	1.01325	14.696	760
1 bar	100,000	100	1	14.504	750.06
1 psi	6,894.757	6.895	0.06895	1	51.715
100 kPa	100,000	100	1	14.504	750.06
760 mmHg	101,325	101.325	1.01325	14.696	760

A handy rule of thumb: 1 bar is very close to 1 atm (about 1.3 percent less), and 1 bar is roughly 14.5 psi. To estimate psi from bar, multiply by about 14.5; to go back, divide by the same.

What are common use cases for a pressure converter?

• Tyres and pneumatics: read a recommended pressure in bar or kPa when your gauge shows psi, or vice versa.
• HVAC and refrigeration: convert system pressures between psi, bar and kPa across mixed-unit specifications.
• Weather and aviation: translate barometric readings between hPa (hectopascals, identical to millibar), mmHg and inches conventions.
• Diving and gas cylinders: move between bar and atm when checking tank pressure and depth equivalents.
• Science, lab and vacuum work: convert mmHg and torr readings to pascals or kPa for SI-based calculations.
• Medical: interpret blood pressure or oxygen readings given in mmHg.

Tips and common mistakes

The most frequent error is mixing up the direction of the factor — multiplying when you should divide. Because psi-to-bar (×0.0689476) and bar-to-psi (×14.5038) look unrelated, it is easy to apply the wrong one; the base-unit method above avoids this entirely by always going through pascals first.

Other things to watch:

• Gauge versus absolute pressure. This tool converts the numeric value you give it. It does not add or subtract atmospheric pressure, so it cannot turn gauge pressure (psig) into absolute pressure (psia) — you must handle that offset yourself by adding roughly 1 atm.
• kPa and hPa confusion. Weather pressure is often quoted in hPa (hectopascals); 1 hPa is 100 Pa, so 1,013.25 hPa equals 1 atm. Do not read hPa as kPa.
• mmHg versus torr. They share the factor 133.3224 Pa here, so they are interchangeable at this precision, but their strict modern definitions differ by a tiny amount.

Limitations and notes

• This converter handles static pressure magnitude only. It does not account for temperature, altitude, fluid density variations, or gauge-versus-absolute offsets.
• Results are shown to seven significant figures, so very small or very large inputs may round in the final displayed digit. For example, 760 mmHg computes to 101,325.02 Pa internally before rounding to 101,325.
• The mmHg and torr factor (133.3224 Pa) is the conventional value; ultra-precise metrology may use a slightly different figure tied to mercury density at a specific temperature.
• For safety-critical, certification or legal work, always confirm against the official figure for your equipment, standard or jurisdiction; this tool is for general reference and estimation.

Related tools

Working in other unit families? Try the length converter for distance, the weight converter for mass, and the area converter for surface area — pressure is force per unit area, so the area converter pairs naturally with it. Browse everything on the converters category page.